The present disclosure relates to a flexible stabilization device for the dynamic stabilization of bones or vertebrae.
A flexible stabilization device for stabilizing adjacent vertebrae is known from EP 0 669 109 B1. In this stabilization device monoaxial bone screws placed in adjacent vertebrae are connected by an elastic strap. The strap is fastened to the bone screws in a pre-stressed manner. A support body which is resistant to compression surrounds the strap between the bone screws to transmit compressive forces. The support body, the heads of the bone screws and the elastic strap form a kind of joint allowing a limited motion of the vertebrae.
US 2003/0220643 A1 discloses a device for connecting adjacent vertebral bodies in which monoaxial pedicle screws are interconnected by a spring. The spring allows spinal flexion and a limited degree of lateral bending and axial rotation while preventing spinal extension without the need of a transverse member. A sleeve is placed over the spring. Impingement between the sleeve and the pedicle screws assists the spring in preventing spinal extension. The length of the spring is predetermined. An adaptation in length by the surgeon is not possible.
WO 2004/105577 A2 discloses a spine stabilization system with one or more flexible elements having an opening or slit in form of a helical pattern. Adjustments of the system with regard to its flexible characteristics are not possible during surgery.
A bone anchoring device comprising a monoaxial bone screw and a flexible rod which is made of an elastic material is known from EP 1 364 622 A2. The elastic characteristics of the bone anchoring device are determined by material and the shape of the rod which cannot be modified by the surgeon. Furthermore, the use of monoaxial bone screws limits the possibility of adjustment of the position of the shaft relative to the rod.
Based on the above, there is a need for a flexible stabilization device for dynamic stabilization of bones or vertebrae which allows modification of the elastic characteristics of the device and at the same time the adaptation of the length of the rod construct during the surgical operation.